Re: [PATCH v8 03/29] iommufd/viommu: Explicitly define vdev->virt_id

[Vasant Hegde <vasant.hegde@amd.com>]

On 7/5/2025 6:43 AM, Nicolin Chen wrote:
> The "id" is too genernal to get its meaning easily. Rename it explicitly to
> "virt_id" and update the kdocs for readability. No functional changes.
> 
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> Reviewed-by: Pranjal Shrivastava <praan@google.com>
> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant

> ---
>  drivers/iommu/iommufd/iommufd_private.h | 7 ++++++-
>  drivers/iommu/iommufd/driver.c          | 2 +-
>  drivers/iommu/iommufd/viommu.c          | 4 ++--
>  3 files changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
> index 4f5e8cd99c96..320635a177b7 100644
> --- a/drivers/iommu/iommufd/iommufd_private.h
> +++ b/drivers/iommu/iommufd/iommufd_private.h
> @@ -634,7 +634,12 @@ struct iommufd_vdevice {
>  	struct iommufd_object obj;
>  	struct iommufd_viommu *viommu;
>  	struct device *dev;
> -	u64 id; /* per-vIOMMU virtual ID */
> +
> +	/*
> +	 * Virtual device ID per vIOMMU, e.g. vSID of ARM SMMUv3, vDeviceID of
> +	 * AMD IOMMU, and vRID of Intel VT-d
> +	 */
> +	u64 virt_id;
>  };
>  
>  #ifdef CONFIG_IOMMUFD_TEST
> diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
> index 2fee399a148e..887719016804 100644
> --- a/drivers/iommu/iommufd/driver.c
> +++ b/drivers/iommu/iommufd/driver.c
> @@ -30,7 +30,7 @@ int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
>  	xa_lock(&viommu->vdevs);
>  	xa_for_each(&viommu->vdevs, index, vdev) {
>  		if (vdev->dev == dev) {
> -			*vdev_id = vdev->id;
> +			*vdev_id = vdev->virt_id;
>  			rc = 0;
>  			break;
>  		}
> diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
> index 25ac08fbb52a..bc8796e6684e 100644
> --- a/drivers/iommu/iommufd/viommu.c
> +++ b/drivers/iommu/iommufd/viommu.c
> @@ -111,7 +111,7 @@ void iommufd_vdevice_destroy(struct iommufd_object *obj)
>  	struct iommufd_viommu *viommu = vdev->viommu;
>  
>  	/* xa_cmpxchg is okay to fail if alloc failed xa_cmpxchg previously */
> -	xa_cmpxchg(&viommu->vdevs, vdev->id, vdev, NULL, GFP_KERNEL);
> +	xa_cmpxchg(&viommu->vdevs, vdev->virt_id, vdev, NULL, GFP_KERNEL);
>  	refcount_dec(&viommu->obj.users);
>  	put_device(vdev->dev);
>  }
> @@ -150,7 +150,7 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
>  		goto out_put_idev;
>  	}
>  
> -	vdev->id = virt_id;
> +	vdev->virt_id = virt_id;
>  	vdev->dev = idev->dev;
>  	get_device(idev->dev);
>  	vdev->viommu = viommu;